FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: JimNolan on August 04, 2015, 11:33:39 AM
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Guys,
I'm having a heck of a time with my 410. Last week I went drag racing, everything OK. Drove the car that week, no problem. But, I went to a car show Saturday morning and it fouled a plug on #2 cylinder. I've done a compression check on that bank after running the engine a long time. #1-130lbs, #2 140lbs, #3-130lbs, #4-130lbs. ( I think #2 is high because of oil and crud that wasn't burnt) ( I did compression check with all cylinder plugs out).
The engine vacuum is 17 inches idling at 650 rpm. May fluctuate back and forth from 17-16 1/2 inches, more or less steady. I rev it and it goes to @8 inches and then to 26 inches before settling back on 17. Plug is always wet and when you take it down the road high vacuum on deceleration draws oil into cylinder and then burns it when you accelerate again. It will idle showing no smoke out the exhaust but when you put in under load it acts as if I've got bad rings. Changed wires and distributor cap, plugs too.
I called Edelbrock and ask them if they had trouble with valve seals popping off and they said it was unlikely. Cars got about 20K miles on it and @60 drag races. HELP. What do you think.
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Could have a dropped valve guide but more likely a bad valve seal. If you can do a leakdown test as well, that would rule out cylinder damage. Then, pop the intake spring on that cylinder using the rope trick, air or both. Did you check by hand the outer perimeter of that intake's valve spring for possible breakage?
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I've got to weld a fitting on a spark plug to put air in the cylinder so while I'm at it I'll use my leak down gauges to check cylinder also. Don't really think I've got a bad cylinder though. Springs are in good shape.
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maby intake gasket?
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Fel-Pro intakes?
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Just did leak down test. #4 good cylinder 70/80. #2 bad cylinder 70\80. By running 17 inches vacuum steady an intake leak doesn't seem possible or have I been confused on how to read a vacuum gauge.
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Leakdown #'s look good yet both valves are closed for said test. Agree that the high vacuum readings would be at odds with a bad intake gasket. Yet, what's clearly wrong is still a mystery. Oil then can only be entering via a messed up oil ring (would have zero effect on a compression test or leak-down test) the guide/valve seal or.... I'm also wondering about the intake itself especially an old OEM unit that may have develop a cracked runner on the bottom side.
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The intake is a Edellbrock RPM bought when I bought the heads. I used Fel Pro gaskets (the old style) and I laid a thin layer of High Temp RTV around each intake port, top and bottom as well as the water jackets. I never intended to take them off again and I never intended to take a chance of them leaking. The leak down test was done with a luke warm engine but the comparison is what I was looking for. If the engine had been hot I'd have gotten a better reading on the leak down.
I've got to be pulling this oil through the valve guides, can't figure out where else it could be coming from. Since I've got the fitting made now to put air in the cylinder I'll take the rockers off and put air in the cylinder and take the intake springs off and see what it looks like.
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Fel-Pro intakes?
Dam.. I sometimes use reg old Mr gasket 202A's and never have had a prob like this.
Maybe a clearance or fitment issue .
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Actually, one more thing: the pushrod area on the RPM, like all FE intakes, is exposed to oil on a number of sides compared to other engines. With some high lift cams, one sometimes has to ream or bore out the p-rod holes to avoid rubbing. But, IIRC, the RPM's p-rod holes are well placed and likely did not need to be opened up. Could a casting flaw in this area be present?
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Do you know if the heads had teflon seals, or viton seals on the guides? The teflon will let oil by very easily if one of them has been dinged anywhere along the assembly process. I refuse to use teflon on anything for the street because I have seen the oil streaking out the guides on so many heads that have come to me for porting. For race, and yearly refresh, teflon works, but not long term for the street. Joe-JDC
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Joe-JDC, Edelbrock uses the 9726 Viton seals on my 60069 heads. They claim they don't have any problems but I've found forums on the internet that says they've had them pop off under street use after 5000 miles. Tomorrow I'm pulling the springs and checking the seals. I'll change the seals on the problem cylinder just to be safe. Advance Auto sells their valve seals. I've heard horror stories about the Teflon seals, right now I wish I had the old umbrella seals, I know they last a long time.
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I've heard horror stories about the Teflon seals, right now I wish I had the old umbrella seals, I know they last a long time.
I'm not sure about that, the umbrella get old and brittle and break and are less than ideal for oil control. Teflon are touchy, but viton are a good option. Jmo.
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I was just kidding about the umbrella seals but best of my recollection the one's on my 1966 Fairlane GT I owned were still good at 120,000 miles. I really don't know how far advanced you get when you put valve seals on your car that lasts 20,000 miles. And intake gaskets is another one. Don't remember needing to check those at 20,000 miles either. I love progress. lol
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Unfortunately the problem that many run into is that these aluminum heads grow more than iron heads with heat cycle, and the clearances need to be correct for oil control at running temperatures. Some of the guides are not finished to the proper sizes, and that causes one stem to be either tighter or looser than it should be, and it will use oil after the seal wears a small amount. A guide that is tight to start will scratch the stem if it does not seize the valve, and those scratches can wear on the seal over time, causing oil to seep by at a slightly greater rate. The bigger the valve stem, the bigger the problem. Also, some of these viton style seals are color coded for intake and exhaust usage, and if someone puts the wrong seal on the wrong valve, they wear quicker. There are seals that are made for .500 guides, .530 guides, and if you mix those up, the .530 seal will pop off a .500 guide. Of course they should have been correct from Edelbrock. I have found heads that had seven guides properly sized, and the eighth guide was not touched after installation other than deburr the end where it was driven in. Human error, someone just forgot to double check themself. Just saying. Joe-JDC
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Joe-JDC,
I'm having a set of C1AE heads reconditioned by a new machinist I've never dwelt with before. This is going on a 390 build I'm doing. And, I was telling him the problem with my 410 fouling the plug on one cylinder and going through leak down, compression and vacuum test. He has worked on FE's for a long time and he said you probably got a intake leak and my reliance on the vacuum test I did to eliminate the possibility of an intake leak wasn't justified. He said I could still get good readings because the motor was big.
What's your take on that. I'll be finding out tomorrow anyway when I lift the springs off that cylinder. Thanks
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Did I understand you to say it only smokes when accelerating after a decel? If so, then that sounds like you might have an intake leak on the #2 port. Is your PCV hose routed to both planes? or one runner? Is it using any oil? Slow drain back on the right bank might also allow oil to pool and get by an exhaust guide and smoke on acceleration because of oil level covering the seal/guide. The early Edelbrock heads did not have a good drain machined in them, so I hope you double checked that upon assembly. If you have recent castings, they have a better placed oil drain back. Joe-JDC
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Sure does sound like an intake gasket sucking oil. It could have done it when you ran it hard at the strip.....It could still show good vacuum on a guage.
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Pressure checking the intake is possible. A bit of a pain - but might be worth it on a real problem child. We've found some really sneaky leaks doing it - like "blind hole" carb studs that vacuum leaked around the threads, and leaky pushrod holes through porosity in the castings that sucked oil.
Remove the rocker assemblies. Plug ALL the vacuum passages. Make a carb block-off plate (kinda like a motor lift plate) and drill a single hole in the carb area & thread it for 1/8" pipe. Hook up a pump style radiator pressure tester and pump up 10 or 15 pounds of pressure - see if it holds. You can hook up shop air and use the regulator from a leakdown tester for continuous checks - but you might need to turn off the air compressor to hear what's happening. While its leaking you can listen & soapy water check for the places the air is going. Be prepared to listen to seeping valves and hissing fittings that you thought were perfect.
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Joe-JDC,
I have the better heads. When I took the valve cover off (first time in 20K miles) there wasn't a lot of oil at all standing in head. All the components had a good oil film on them but no standing oil. The engine doesn't smoke while idling but if you rev the engine and let off the next time you rev it you'll see some smoke. The real smoke comes under load when you run it up through gears and let it coast for a bit. When you get on it the next time it looks like a freight train behind you. My buddy took a video of me drag racing and it didn't blow any smoke then. It was the next weekend that I went to a car show never putting any stress on the motor that it started smoking. The seals are going to be here this morning (love Summit, order one morning, get what you ordered before 12:00 the next morning) and I'll pull the intake spring on that cylinder and check the seal.
Barry R,
I'll remember what you said about pressure checking an intake but if the valve seals are good the intake gets pulled anyway. I hate that too because I put a thin film of RTV on the bottom and top of each intake and exhaust opening to each cylinder as well as the water jackets, it's going to be a mess to clean up. The block was a remanufactured 352 for a passenger car that I had the machinist just clean up the deck to ensure geometry of the head intake angles. I felt secure using new heads/intake and the old Fel-Pro gaskets with RTV backup. I don't think I could put it together any better. This new guy that's doing my cast heads says my 25 lb. torque on the intake bolts should have been 35 lbs. though. Just to save some time of me asking, please give me a part number of the intake gaskets you use on your builds.
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Not sure if this is the same pressure testing as was referred to above.
Here is a video I made of pressure testing the intake on a 351w.
https://www.youtube.com/watch?v=YBS56WRluDg
I could only control the volume of air that went in as I didn't have a regulator on it. But, you could hear the air escaping. It was coming through the crankcase. Putting my hand over the valve cover was fun to make music---but quite annoying to watch.
My thought was the intake gaskets were leaking. The gaskets that came out showed lines of being compressed at the top, but faded towards the bottom. I replaced the intake gaskets with ones that had the printed ring around each port for sealing and the car idled a little better. It's still has a shake to it, just as bad as it ever was. Bothers the heck out of me actually. Thinking about it now, the machinist said he never had to take so much off a block to square the decks. I wonder if there is some misalignment between the intake port face of the head to the manifold. Maybe the intake needs to be resurfaced to make the surfaces parallel.
I don't want to hi-jack the thread with some 351w stuff, but perhaps there is some info hidden in my rambling that sparks an idea.
thanks,
Mark
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Mark,
When I put the engine together I bought a used Streetmaster intake because Jay B. raved about it so much. Even wrote a book about it. I set it down on my new Edelbrock heads and I swear you could rock it back and forth. It was warped real bad. So, I ordered the Edelbrock RPM intake. When I set it down on the heads it was rock solid, the holes lined up very well and trying to use a feeler gauge top and bottom of each corner showed it was sitting flat. I've never had leaks front or back using RTV as gaskets for that area and for 20K miles this engine has run great. I'll watch your video. Thanks for the reply.
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Just got through taking valve spring off #2 intake. Wasn't anything wrong with the seal.
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Do you restrict the oil feed to the rockers?
On my Ed's I have a .070" plug in the heads and have LOTS of oil up top.
I could even put a smaller hole plug in and still have lots of oil in the heads.
I have watched the rockers with a cut open cover and the oil was spilling over the top. ::)
The Ed's also have a smaller than stock oil return hole and I drill it out larger.
And also work the drain back between the head and intake.
Could you be flooding the heads?
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I don't use drip rails under the rocker stands but there is no oil to amount to anything on top of the head when I take the valve covers off. I've got a Precision Pumps oil restrictor in there and besides that. I've put 20K miles on this motor without problems. It happened all of a sudden.
One of the guys I flew with has a bore scope that we're going to look at the cylinder wall with. I won't be able to see the oil control ring but I'll be able to see if there's damage to the cylinder wall.
After that I'll pull the intake. And, I lied to you guys, I thought I used a old style Fel Pro intake gasket. My intake gasket has the word Edelbrock all over it.
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It is sounding more and more like an intake gasket failure. Joe-JDC
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It is sounding more and more like an intake gasket failure. Joe-JDC
Joe, you know it's probably an intake leak. But, now you can say that a vacuum gauge doesn't always detect intake leaks. At least mine didn't.
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It is sounding more and more like an intake gasket failure. Joe-JDC
Joe, you know it's probably an intake leak. But, now you can say that a vacuum gauge doesn't always detect intake leaks. At least mine didn't.
I would add that an intake gasket leak RARELY shows on a gauge. If you think of the volume of a couple/three pistons dropping in sequence, and the size of the intake plenum, a small leak will likely not show on the total vacuum shown on the gauge, although it will change a/f mixture and add oil dilution for that specific cylinder. Matter of fact I am considering unhooking a PCV on the truck I am working on tomorrow (396 FE) to see how much the vac gauge changes. That'll be a 3/8 hose off #4 port, so it should be dramatic compared to a seepy gasket:)
Your problem sounds like an intake leak.
BTW, I saw you mention umbrella seals, get their perceived success out of your head :) They were oil deflectors, not seals, they did OK compared to Chevy O-rings, and for long term, they likely outlast Teflon seal (but not outseal at the beginning, regardless I hate those hard plastic seals), but compared to modern positively located Viton, unbrellas are not very good.
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A quick easy test for a vacuum leak on an intake gasket(non FE) or any vacuum hose, connection, etc, is to spray either carb or brake cleaner around the suspected area and watch the idle and/or a/f ratio(for efi) to change while doing it. You can also use a propane bottle for a torch with a small nozzle and valve to do the same thing. This would be a little harder on an FE unless you had a cut open valve cover to control the oil while running, and you would probably want to go the propane route to not dilute the oil too much with the cleaner just in case.
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Well, the intake is off, cleaned up and new gasket ready to put back on. The drivers side gasket looked good, the passenger side gasket had slide somewhat when it was installed and I had numerous places on #2 intake that only covered a small portion of the gasket. The gasket itself was broken in to between #2 and #3. Don't ask me, I have no idea. If this isn't the problem it's missed a good chance anyway.
I plan on using "the right stuff" this time and covering the head side of the gasket with a thin layer of RTV. I think I'll let it set for a couple hours before I put another thin layer of RTV on the intake side of the gasket. Then I'll install the intake.
Thank each and every one of you for you help and suggestions. Jim
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Jim, good to hear feedback. A suggestion: enlist someone to help when plopping that big intake back on. Heck, even in aluminum....it's a bear! ;D
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I would skip the RTV altogether.....
Use the Right Stuff, TA-31, Dow-Corning silicone, or similar. Put a small smear around every port on the heads, lay the gaskets down, then set the intake on it and let it sit overnight. Go back the next day, smear some more on the gasket around the ports, lay your beads down for the end gaskets, then set the intake on, start the bolts, set the distributor (make sure intake is centered around it), then tighten her down.
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I would skip the RTV altogether.....
Use the Right Stuff, TA-31, Dow-Corning silicone, or similar. Put a small smear around every port on the heads, lay the gaskets down, then set the intake on it and let it sit overnight. Go back the next day, smear some more on the gasket around the ports, lay your beads down for the end gaskets, then set the intake on, start the bolts, set the distributor (make sure intake is centered around it), then tighten her down.
When I said RTV I meant "The Right Stuff". I called NAPA earlier today and they had two calk containers of it. They laid one back for me. I'll do it like you suggest. One more day after all this isn't going to hurt me. Thanks, Jim
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Update:
Just to let you guys know, the engine is back together. I noticed one thing this time that was different from the first time I put it together, the intake bolts dropped right into place and tightened by finger without moving the intake around to get the bolts in. Have no idea how it lasted for 20K miles like it was, but it did. I can rev the engine now without making smoke. It still has 17 inches manifold pressure and the gauge still acts the same as before. Taught me a lesson. Thanks again everyone. I'd never have thought the vacuum gauge wouldn't have indicated a vacuum leak.
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Great! Happy FE'ing!